A number of research organizations have been investigating the use of projection based display systems as an approach for providing an enhanced view of computer results. The results of the research are displayed in stereo on a large flat surface. The researcher wears a head tracked pair of stereo flicker glasses and looks at the table top where an image from a computer is projected on the surface by a video projector. The computer produces a stereo pair of images which the viewer sees. Computer generated objects appear to be in and above the table from the viewer's perspective. This invention is a novel implementation of such a display table which offers an additional unique and useful feature--the table top can be adjusted to an inclined position thus providing a larger stereo working volume.
1. Field of Invention
This invention relates to the field of stereo projection and immersive computer interfaces.
1. Description of the Prior Art
Several research groups including GMD in Germany, Stanford University in California, Naval Research Labs, NASA Ames, and others have developed visualization systems which are based around a flat projection table. A table with a translucent surface (generally about 4 foot by 6 foot) is constructed and a mirror angled beneath the translucent surface. The angled mirror reflects light from a video projector located behind the table onto the translucent surface. The projector is driven by a computer. Rather than simply have the images from the regular computer monitor appear on the large table top, the computer and projector are set up to display a stereo pair of images (field sequential stereo) on the table top. The user wears stereo glasses (such as those for Tektronix.TM. or StereoGraphics.TM.) when looking at the images on the table top. Thus, the viewer sees a stereo image on the table top. This system is further enhanced by the use of a head tracker. The head tracker is attached to the viewers head (or the stereo glasses) and is used by the computer in re-computing the images projected on the table. The data from the head tracker (typically an Ascension or Polhemus) permits the computer to recalculate the image in such a way as to make it appear as if there is an actual "object" on/in the table. Thus, one can look at a coffee cup on the table and look around at the other side of it by walking around the other side of the table.
This arrangement means that the users working volume is as shown in FIG. 1--the virtual objects must, ideally, be contained in the virtual cone as shown.
In addition, other research groups, most notably at Sun Microsystems and University of Illinois, have taken a different approach in which these environments are presented on predominantly vertical walls on which stereo images are presented. A full room constructed in this way is known as a Cave and a single wall Cave is known as an Immersadesk. These approaches offer a larger viewing volume than the table top methods. A predominantly vertical projection surface does however create a very different immersive experience with different limitations--for instance it is impossible to look down on an object.